12.2 Climate-Driven Demography
197
figures, in a column on the left. We have also added an estimated founder population of 3,000 and an initial growth rate of 1.39% p.a. This growth rate matches the
highest such figure in the table (1.39% for the period 1901–1960). This period is
undoubtedly closer in temperature than any other in the table to the warmth of the
Medieval Climatic Optimum, when demonstrably after 235 years of warm conditions, the population had reached 77,520 [7]. The high initial growth rate for Iceland
is consistent with its being an agricultural society with sheep and cattle and pigs, initially able to maintain contact with its homeland, able to grow several cereal crops
and possessing an enslaved labour force (possibly not represented in Thorarinsson’s
data).
Table 12.1 shows the peaking of population following the favourable conditions
of the Medieval Climatic Optimum, then a long, slow, continuous fall in population
with the advent of the Little Ice Age. There is, indeed, a 689-year period of continuous population decline in Iceland from AD 1095 to AD 1784. In Greenland the
same pattern of population peaking in the Medieval Climatic Optimum and falling
drastically in the Little Ice Age occurs, but the outcome for the population of this
Norse settlement was extinction. The Icelandic population survived, but it took 800
years for Iceland’s population at AD 1095 to be reached again.
The demographic pattern we see in Iceland in this very clear example, with demographically unimpeachable data, is found throughout northern Europe, though often
there famine is tied to harvest failures in specific years or decades during the Little
Ice Age. Lamb, comparing Iceland and Scotland, for example, notes that “in the
upland parishes in Scotland, in the successive harvest failures in the 1690’s, it has
been estimated that about one third of the population died”. It was this catastrophe that forced Scotland into union with England [8] and prompted the Scottish
colonization of Ulster. Aimed at reducing the population burden in Scotland, this
migration led to the sectarian conflict in Ireland that has lasted down to the 21st
century.
These examples from Iceland, Greenland and Scotland all show the demographic
consequences of extreme climate change for populations which have reached their
ceilings of sustainability. If extreme climatic conditions reduce food resources in
these circumstances, survival ceilings are independently lowered. Starvation follows
and, as we see from the Norse colony in Greenland, this can lead to population
extinction.
Though all three European examples record the effects of global climate change
on demography, it is clear from Lamb’s wide-ranging study that the expressions
and consequences of global climate change in different parts of the world, even
though driven by the same global climate extremes, may not be synchronous or
comparable. In different parts of the world, the extremes both in good and adverse
conditions and in population increase and decline, driven by differing expressions
of the same global climate patterns, can vary markedly. There can be considerable variation both within and between hemispheres and between latitudes, with
local, regional and global conditions in concert affecting outcomes for different
areas.
197
figures, in a column on the left. We have also added an estimated founder population of 3,000 and an initial growth rate of 1.39% p.a. This growth rate matches the
highest such figure in the table (1.39% for the period 1901–1960). This period is
undoubtedly closer in temperature than any other in the table to the warmth of the
Medieval Climatic Optimum, when demonstrably after 235 years of warm conditions, the population had reached 77,520 [7]. The high initial growth rate for Iceland
is consistent with its being an agricultural society with sheep and cattle and pigs, initially able to maintain contact with its homeland, able to grow several cereal crops
and possessing an enslaved labour force (possibly not represented in Thorarinsson’s
data).
Table 12.1 shows the peaking of population following the favourable conditions
of the Medieval Climatic Optimum, then a long, slow, continuous fall in population
with the advent of the Little Ice Age. There is, indeed, a 689-year period of continuous population decline in Iceland from AD 1095 to AD 1784. In Greenland the
same pattern of population peaking in the Medieval Climatic Optimum and falling
drastically in the Little Ice Age occurs, but the outcome for the population of this
Norse settlement was extinction. The Icelandic population survived, but it took 800
years for Iceland’s population at AD 1095 to be reached again.
The demographic pattern we see in Iceland in this very clear example, with demographically unimpeachable data, is found throughout northern Europe, though often
there famine is tied to harvest failures in specific years or decades during the Little
Ice Age. Lamb, comparing Iceland and Scotland, for example, notes that “in the
upland parishes in Scotland, in the successive harvest failures in the 1690’s, it has
been estimated that about one third of the population died”. It was this catastrophe that forced Scotland into union with England [8] and prompted the Scottish
colonization of Ulster. Aimed at reducing the population burden in Scotland, this
migration led to the sectarian conflict in Ireland that has lasted down to the 21st
century.
These examples from Iceland, Greenland and Scotland all show the demographic
consequences of extreme climate change for populations which have reached their
ceilings of sustainability. If extreme climatic conditions reduce food resources in
these circumstances, survival ceilings are independently lowered. Starvation follows
and, as we see from the Norse colony in Greenland, this can lead to population
extinction.
Though all three European examples record the effects of global climate change
on demography, it is clear from Lamb’s wide-ranging study that the expressions
and consequences of global climate change in different parts of the world, even
though driven by the same global climate extremes, may not be synchronous or
comparable. In different parts of the world, the extremes both in good and adverse
conditions and in population increase and decline, driven by differing expressions
of the same global climate patterns, can vary markedly. There can be considerable variation both within and between hemispheres and between latitudes, with
local, regional and global conditions in concert affecting outcomes for different
areas.